Energy storage systems are used to store energy generated by various energy sources, such as renewable energy sources (e.g., solar, hydroelectric, wind, and/or geothermal sources) and/or other energy sources (e.g., fossil fuels, natural gas, nuclear, coal, etc.). In some applications, energy storage systems are used for grid-scale storage to help balance differences between energy supply and demand. For example, some renewable energy sources may generate energy during periods of low energy demand, and the excess energy may be stored until demand increases, at which time the stored energy may be supplied to meet the increased demand. Various approaches for energy storage include pumped hydroelectric energy storage, compressed air energy storage, and electrochemical energy storage in one or more batteries.